I would only add that those details need to be consider during design, not after the design.
Ralph From: Douglas Nix <[email protected]> Sent: Wednesday, August 30, 2023 6:31 AM To: [email protected] Subject: Re: [PSES] DFMEA Component Selection Hi Mike, I agree completely. These are the details that, after the design, can make or break a product.. -- Doug Nix [email protected] <mailto:[email protected]> When you put a thing in order, and give it a name, and you are all in accord, it becomes. >From the Navajo, Masked Gods, Waters, 1950 On Aug 29, 2023, at 17:18, MIKE SHERMAN <[email protected] <mailto:[email protected]> > wrote: Doug speaks from experience similar to mine---the standards tend to do a good job of addressing risks, so it's good to spend some time on things maybe not explicitly covered in the standards. My pet peeve list includes workmanship issues, such as properly torquing all terminal connections, especially those on components. Plus routing, bundling, and securing the wiring correctly (e.g., properly segregating low voltage wiring). And only stripping the specified length on line voltage conductors where they enter components, to reduce the risk of touch shock. These are the kind of details a good UL 508A panel shop will do for you if you contract it out. Conversely, these are things you have to come up to speed on if you do the work in house. Another thought: not only is the designer a good person to have in on the analysis, but also bring in a field service technician for a reality check on how things are actually used (I love Doug's photograph!). Mike Sherman Sherman PSC LLC On 08/29/2023 4:01 PM CDT John Allen <[email protected] <mailto:[email protected]> > wrote: Very good point on the Designer to be a part of it. You may consider a HARA vs an FMEA to get to the bottom of your question. To Rich Nute’s point a long time ago to me – what are the hazards we are concerned about?? A Hazard Analysis Risk Assessment is a top down approach of Hazards vs an FMEA calling out each part and what can go wrong. HARA asks what are all the Hazards associated with this product/system/event. What in the design mitigates against those hazards? What tests can I do to prove those mitigating factors work? and is that adequate? There are many ways to understand overall safety of a product/system/event – FMEA, HARA, HAZOP, etc. We should work to a common way or even some guidance in this area. The LVD says a “risk assessment shall be in the technical documentation”. Thanks for the guidance!! If there are any leaders in this group regarding such I’d love to discuss possible Hazard Analysis and Risk Assessment methodologies and Standard(s). Along with a PSES Technical Committee and Track at ISPCE. Best Regards and Be Safe, John John Allen | President & CEO | Product Safety Consulting, Inc. 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From: Douglas Powell <[email protected] <mailto:[email protected]> > Sent: Tuesday, August 29, 2023 3:12 PM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] DFMEA Component Selection [EXTERNAL EMAIL] DO NOT CLICK links or attachments unless you recognize the sender and know the content is safe. I have always considered that the design engineer, who is most familiar with the product, needs to be involved in DFMEA and forthcoming about potential difficulties. And it's not just about components but also various use models ranging from manufacture to servicing to the end user. A hypothetical example: a heavy module installed in a high location, requiring handling by two people. And cases of foreseeable misuse are also part of this. My favorite example is this photo of a man using the electrical panel of a pivot sprinkler to get a view of something in the distance. The securement of that panel is obviously not designed to carry that much weight. This is a photo I found online, and I have no idea who it is. <image006.jpg> In general, certified components used within their ratings are not as big a concern, but it is good practice to include them in any case. When performing a DFMEA, you want to focus on identifying failure modes that are not explicitly covered by existing safety standards. This involves looking beyond the standard's prescriptive requirements and considering potential failure scenarios that could arise due to the unique nature of the component, device, or product and the way it is being used. Keep in mind that FMEA, of any type, is generally a bottom-up approach, whereas FTA is top-down. Using the two in conjunction has sometimes been referred to as a Bowtie Analysis. -Doug Douglas E Powell Laporte, Colorado, USA <mailto:[email protected]> [email protected] <https://www.linkedin.com/in/coloradocomplianceguy/> LinkedIn (UTC-06:00, US-MDT) On Tue, Aug 29, 2023 at 1:30 PM Ronan Shanley <[email protected] <mailto:[email protected]> > wrote: Hi All, We are going through a DFMEA process for an enclosure we have designed but are having trouble determining which components to analyze. We know we want all the safety rated components and likely the upstream components of those as well. We’re unsure if we should include components related only to functionality or how granular we should get with the components upstream of the safety components. For example do we include the wire feeding the safety controller or what about the terminal blocks? Is anyone familiar with where the limit for component criticality usual falls for DFMEAs? 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